The prior art cable fire barrier blanket is described in U.S. Pat. No. 4,822,659 issued Apr. 18, 1989. This blanket has a rectangular portion with lengthwise interlocking strips along two opposite lengthwise edges and has a first inner fiberglass layer with the strip and has a second adjacent insulating material layer and has a third adjacent fiberglass layer and has a fourth outer foam rubber layer.
One problem with the prior art cable fire barrier blanket is that it is relatively difficult to make a good connection between the blanket and an electrical cable or conduit. A second problem is that it is an expensive type of construction.